Device to facilitate drawing of straight lines



1943- J. E. ENTRIKEN 2,331,669

DEVICE TO FACILITATE DRAWING 0F STRAIGHT LINES Filed Dec. 50, 1942 INVENTOR J4me; 5 fair kq Y m Szmlm m,

ATTORN EYS Patented Oct. 12, 1943 TO FACILITATEDRAWINGOF I STRAIGHT LINES JamesE. Entriken, Bristol, Pa, assignor, by, 1

mesn'e assignments, to Reconstruction Finance Corporation Application December 30, 1942',

8 Claims.

This invention relates to a device to facilitate drawing straight lines of considerable length with greater speed and accuracy.

Where drawings of airplanes',.ships and the like are made on a large scale, it is necessary to define straight lines much longer. than the usual straight-edge employed ordinarily in drafting. In the conventional method of defining such lines, a piano wire is stretched under considerable tension between two fixed points along the lofting platform about one-half inch above the surface. The loftsman then, takes his square or steel block and moves it into contact with the stretched wire. To work accurately, he must examine the point of contact through a magnifying glass. When he is satisfied that the contact is accurate, the loftsm'an marks the loft surface and proceeds to determine other points. Finally, the points are connected with the aid of a straight-edge.

It is extremely difficult, even when a magnifying glass is used, to determine the point of con tact wtih the wire acurately. The element of judgement by the loftsman is a constant source of possible error, audit is frequently necessary to recheck the line several times before itcan be accepted. The procedure is extremely tiring to the loftsman and it consumes a lot of valuable time.

It is the object of the present invention to i provide a, simple, compact and effective device which is adapted to avoid the defects mentioned.

Another object of the invention is the provision of an electrically activated device to in dicate quickly to the loftsman the point of reierence which he wishes to establish.

Other objects and advantages of, the invention will be apparent as it is better understood by reference to the following specification and the accompanying drawing, in which i Fig. 1 is a View in perspective illustrating the device and its application;

Fig. 2 is a longitudinal section through the device;

Fig. 3 is a plan view of the under surf the device;

Fig. 4. is an enlarged View illustrating the conace of I tact mechanism of the device; and

Fig. 5 is a section on the line 5-5 of Fig. 2.

Referring to the drawing, 5 indicates a lofting surface and B a tensioned wire above the surface arranged to permit determination of the desired line. These are conventional arrangements as previously indicated.

The device I, forming the subject matter of Serial No. 470,701

the invention; comprises a housing 3 of Wood or plastic or preferably of metalto aifordthe desired weight so that the device will not be too easily moved from any'position on the loiting surface 5. A recess 9' in the housing 8 aiiords space fora dry cell battery Hi having a pole l l which is adapted to engage a contact terminal !2 consisting preferably of a, dished metal disc resting against an abutment at the end of the A lamp socket Nils dispcsedin the recess 9. recess above the: battery It and engages the outer shell-thereof. A lamp M is disposed in the socket. r

A slidable member i5. is supported by screws it in the bottom ofthe device and is biased by a spring I! bearing on a" shoulder is and on the upturned end it of the member it; against a screw having a' head H which is adapted for manipulation. Thus the member i5 may be advanced or retracted by adjustment'of the screw 28.

Near its outer end the member 15 is provided with a post 22 carrying a'metal washer 23 which is connected by a wire 2.4 to the contact terminal I2. An insulating washer 25 is disposed on the post 22. and a second metallic washer 28 is disposed above" it and con'nected by a wire 27 to a clip 28 which engages the lampsoclretit.

' loftsman places the device 1 in position so that The washer 25' carries a whisker 29 in the.

form of a stiff but flexible wire bent to provide a depending leg 30 which is adapted to engage the wire 6 above the lofting board. A Washer 31 and an insulating sleeve 32 hold the washer Eli in place on the post 22. The whisker 29 is thus connected electrically to the lamp socket it while the washer 23 is connected to the contact terminal I2 and the whisker is normally insulated from the washer 23. When the whisker engages the washer 23, the circuit is closed through the battery and lamp and the lamp is lighted.

In the use of the device, the stretched wire 6 is used as in the conventional operation. The

the leg 30 of the whisker 29 is nearly in engagement with the wire. By turning the screw 2!), the member I5 is advanced until the leg 39 engages thewire 6 and is deflected sufiiciently to engage the washer 23 and close the circuit, thus lighting the lamp 14. The loftsman then reverses the movement of the screw to withdraw the member I5 to the point where the circuit is broken and the lamp I4 is extinguished. He then scribes a mark on the lofting surface 5 at the end of the member I5 with a pencil 33 as indicated in Fig. 2.

Having determined one point, the operation is repeated along the lofting surfac until a sufficient number of points have been scribed. The points can be connected then with a straightedge to form a straight line.

While I prefer to employ a battery as a source of current within the body of the device, current may be derived from any convenient source and supplied through an ordinary extension cord to conductors within the body including the whisker and contact to complete the circuit to the lamp. A low voltage lamp may be used and the voltage of an ordinary lighting circuit may be reduced by the usual transformer. If desired, the wire 6 may be a part of the circuit, thus permitting the use of a single conductor to connect the device to the source of current. These modifications with respect to the source of current are well known adaptations in electrical practice.

As is obvious, the use of the electric current to facilitate the determination of the point desired ensures the maximum possible accuracy with the minimum of effort. The circuit can be closed and opened by a relatively minute movement of the screw 29, and hence each point determined is at precisely the same distance from the wire. No magnifying glass is necessary, and the tedious operation heretofore performed by th loftsman is no longer necessary.

Various changes may be made in the form and arrangement of the device without departing from the invention or sacrificing the advantages thereof.

I claim:

1. A device to facilitate drawing of straight lines comprisin a body having a chamber, a source of electric current therein, a lamp, and a normally open circuit connected to the source of electric current and the lamp including a flexible whisker and a contact adapted to be engaged by deflection of the whisker.

2. A device to facilitate drawing of straight lines comprising a body having a chamber, a source of electric current therein, a lamp, and a normally open circuit connected to the source of electric current and th lamp including a flexible whisker and an adjustable contact adapted to be engaged by deflection of the whisker.

3. A device to facilitate drawing of straight lines comprising a body having a chamber, a

source of electric current therein, a lamp, a normally open circuit connected to the source of electric current and the lamp including a flexible Whisker and a contact adapted to be engaged by deflection of the whisker, a longitudinally adjustable member carrying the contact and threaded means manually operable to adjust the member.

4. A device to facilitate drawing of straight lines comprising a body having a chamber, a source of electric current therein, a lamp, a normally open circuit connected to the source of elec tric current and the lamp including a flexible whisker and a contact adapted to be engaged by deflection of the whisker, and a longitudinally adjustable, resiliently biased member carrying the contact.

5. A device to facilitate drawing of straight lines comprising a body having a chamber adapted to receive a source of electric current, a contact terminal and a lamp socket disposed in the chamber and a normally open circuit connected to the contact terminal and the lamp socket including a flexible whisker and a contact adapted to be engaged by deflection of the Whisker.

6. A device to facilitate drawing of straight lines comprising a body having a chamber adapted to receive a source of electric current, a contact terminal and a lamp socket disposed in the chamber and a. normally open circuit connected to the contact terminal and the lamp socket including a flexible whisker and an adjustable contact adapted to be engaged by deflection of the Whisker.

7. A device to facilitate drawing of straight lines comprising a body, a lamp socket disposed therein, and a normally open electrical circuit comprising conductors connected to the lamp socket and including a flexible whisker and a contact adapted to be engaged by deflection of the Whisker.

8. A device to facilitate drawing of straight lines comprising a body, a lamp socket disposed therein and a normally open electrical circuit comprising conductors connected to the lamp socket and including a flexible whisker and an adjustable contact adapted to be engaged by deflection of the whisker.

JAMES E. ENTRIKEN. 

